Doping in Non-Planar Heterostructures

技术说明：非平面异质结构，特别是核-壳纳米线，相对于传统的平面异质结构，在光电应用中表现出许多比较优势。掺杂剂分布和界面形态的分析是极具挑战性的，然而，限制了对优化结构和性能所需的基本生长过程的理解。本计画研究控制掺杂剂与合金元素在非平面异质结构中的结合、扩散与分离的驱动力，其中异质结构由硅锗与砷化镓铝镓核-壳奈米线所组成。为此，原子探针断层扫描，霍尔效应测量，开尔文探针力显微镜，和显微光致发光被用来与掺杂水平，和波动的组成，电子和光学性能。在器件结构的加工和电输运过程中掺杂剂扩散的数值模拟是基于原子探针研究提供的定量原子尺度成分信息，并与之进行比较。非技术描述：新材料和新形式的传统材料可以改进现有技术，并导致新技术的产生。该项目正在开发一种基本的理解，即如何以新的方式将已知的半导体材料（如硅和砷化镓）组合在一起，以更好地执行重要功能，例如将光能有效转换为电能，反之亦然。研究活动特别关注非平面异质结构，其中“异质结构”表示两种不同材料的组合，“非平面”表示这些材料之间的结具有复杂的三维形式，以便更好地执行关键器件功能。为了分析非平面异质结构的形状和其中微量电荷控制掺杂剂原子的分布，采用了被称为原子探针断层扫描的高度专业化的显微镜。原子探针可以观察到有史以来最小的设备内部，并绘制出所有元素的分布图。该项目通过包括一个“校园合作”计划，在该计划中，与研究的更大目标相关的本科生研究项目是从工业合作伙伴那里征集的，从而从工业角度看待新技术材料的开发。

Technical Description: Non-planar heterostructures, particularly core-shell nanowires, exhibit a number of comparative advantages for optoelectronic applications with respect to conventional planar heterostructures. The analysis of dopant distribution and interface morphology is extremely challenging, however, limiting the understanding of fundamental growth processes that is needed to optimize the structure and properties. This project investigates the driving forces that control dopant and alloy element incorporation, diffusion, and segregation in non-planar heterostructures consisting of both Si-Ge and GaAs-AlGaAs core-shell nanowires. To this end, atom probe tomography, Hall effect measurements, Kelvin probe force microscopy, and micro-photoluminescence are used to relate doping levels, and fluctuations in composition, to electronic and optical properties. Numerical modeling of dopant diffusion during processing and electrical transport in device structures is based on and compared with quantitative, atomic scale composition information provided by the atom probe studies.Non-technical Description: New materials, and conventional materials in new forms, can improve existing technologies and lead to the creation of new technologies. This project is developing a fundamental understanding of how known semiconductor materials, such as silicon and gallium arsenide, can be put together in new ways to better perform important functions, such as the efficient conversion of light to electrical energy and vice versa. The research activity is specifically focused on non-planar heterostructures, where "heterostructure" indicates the combination of two distinct materials and "non-planar" indicates that the junction between these materials has a complex three-dimensional form so as to better carry out key device functions. To analyze the shape of non-planar heterostructures and the distribution of tiny quantities of charge-controlling dopant atoms within them, a highly specialized microscope known as an atom probe tomographic is employed. The atom probe can look inside the very smallest devices that have ever been made and map out the distribution of all the elements that are present. The project incorporates an industrial perspective on the development of materials for new technologies by including a "co-op on campus" program, in which undergraduate research projects of relevance to the larger goals of the research are solicited from industrial partners.